The present invention relates to an apparatus for the treatment and, in particular, the tempering and heating of plastics-material preforms. It is known from the prior art to produce plastics-material containers from so-called preforms in two-stage stretch blow-moulding processes. During this processing these preforms are heated to a defined process temperature in order to permit the shaping procedure during the stretch blow-moulding. In this case the heating is usually carried out by means of infrared radiation. These preforms have an orifice already formed to the final size and a body area still to be deformed.
The material to be processed (PET) is wherein strain hardening results during the stretching. The shaping temperature is very important during this. Use is made of this effect in the production of PET containers in order to optimise the distribution of the wall thickness of the container. In this case, in accordance with the prior art a temperature profile is applied to the preform in particular by way of infrared radiation (or even other radiation sources). The hotter region of the preform is deformed first, until the stretching resistance resulting from the strain hardening is greater than the resistance of the adjacent colder region. The temperature profile described is usually uniform around the periphery and varies in the longitudinal direction of the preform in a manner dependent upon the process. During the production of oval containers, however, not only is use made of this effect with a temperature layering in the longitudinal direction, but it is also adapted to the design of the container by differing temperature layering around the periphery. This process is also known as preferential heating. In this case the sides to be stretched to a greater degree should be heated by a special heating technique to a greater degree than the sides to be stretched to a lesser degree. These heating techniques mentioned are described in numerous documents and in part are also protected.
A process for the precise temperature adjustment of re-heated performs is known from U.S. Pat. No. 3,892,830. Here those sides of the perform which are to be expanded along a main axis are touched with textured fingers in order to lower the temperature. U.S. Pat. No. 632,713 describes a process for blow-moulding whilst using an elongate oval plug. An apparatus for blow-moulding containers is known from U.S. Pat. No. 5,869,110. This apparatus has a heating device for heating a perform as well as a shaping unit in order to shape the perform. In addition, an intermediate region is provided which has a temperature-adjusting device in order to adapt the temperature of at least part of a surface of the perform.
DE 695 18 223 T3 likewise describes an apparatus for heating preforms. Here a temperature-setting member is mentioned which has cool members which are arranged along the axial direction of the preform and which are brought into contact with the container whilst using cylinders or the like. Only light contact is achieved here which does not, however, deform the container. EP 0 920 974 A2 describes an apparatus for blow-moulding non-round containers starting from a rotationally symmetrical preform. This apparatus has a rotation device in order to turn the preforms about their own axis, and a sensor which determines an angular position of each preform in a heating station.
A blow-moulding machine for containers, which contains an apparatus for orientating the preforms in a tool, is known from DE 600 04 894 T2. EP 1 279 477 A1 describes an apparatus and a process for blow-moulding a bottle. In this case, too, the preforms are positioned inside a blow mould between a heating step and a blowing step, wherein a sensor detects profiled positions of each preform, so that these regions are arranged in a pre-set orientation relative to the blow mould.
U.S. Pat. No. 5,101,990 describes a process for blow-moulding containers with oval cross-sections for example. Here ribs directed radially inwards are formed in the containers. In a process known from U.S. Pat. No. 4,151,249 for producing plastics-material containers, inwardly curved ribs are formed. These ribs are produced by contact-free cooling by air in individual regions of the preforms.
The object of the present invention is therefore to make available a new concept for providing the performs with a temperature profile varying in the peripheral direction.